This is a ready-to-use plan for a potency assurance strategy: a system of complementary measures, rather than a single bioassay, that together with process controls assures the biological activity of a cell or gene therapy product across its lifecycle. It reflects the current FDA framing for CGT and active immunotherapy products, that potency can be assured by a matrix of correlated measures where a single quantitative functional assay is not yet feasible at every stage. Replace every <<FILL: ...>> placeholder with your own specifics. A filled specimen follows. This is general guidance to adapt and verify, not legal or regulatory advice.
Document control header
| Field | Entry |
|---|---|
| Document title | Potency Assurance Strategy, <<FILL: product>> |
| Document number | <<FILL: PLAN-ID, e.g. POT-STRAT-001>> |
| Version | <<FILL: version, e.g. 1.0>> |
| Effective date | <<FILL>> |
| Product / stage | <<FILL: product, phase or commercial>> |
| Plan owner | <<FILL: role, e.g. Head of Analytical Development>> |
1. Scope and objective
This plan defines the potency assurance strategy for <<FILL: PRODUCT>> across <<FILL: development stage through commercial>>: which measures assure potency, how they correlate to the relevant biological activity, and how the strategy evolves as the product moves toward licensure. It applies where a single, fast, quantitative functional assay is not yet available at every point in the lifecycle (short shelf life, small lot size, complex or partially understood mechanism), and it does not replace the individual assay validation protocols it references.
2. Why a single assay is not enough
State the product-specific reasons a single potency assay does not, by itself, assure biological activity at this stage. Typical reasons for CGT products: a mechanism that may act through more than one pathway, a live and heterogeneous product, a short shelf life that does not allow a slow functional assay to read out before release, limited lot size, and inherent bioassay variability. <<FILL: product-specific rationale>>.
3. The potency assurance matrix
Each measure in the matrix contributes to the overall potency claim. No single row is expected to carry the full burden; the anchor functional assay is the one closest to mechanism of action, and the other rows support release timing and characterization while the correlation to function is built.
| Measurement | Assay | Reads on | Release or characterization | Status |
|---|---|---|---|---|
<<FILL: e.g. cell viability>> | <<FILL: flow / dye exclusion>> | <<FILL: live active cells present>> | <<FILL: release>> | <<FILL: qualified / validated>> |
<<FILL: e.g. identity / phenotype>> | <<FILL: flow cytometry>> | <<FILL: correct cell population, transduction marker>> | <<FILL>> | <<FILL>> |
<<FILL: e.g. transgene expression>> | <<FILL: flow / qPCR>> | <<FILL: construct is expressed>> | <<FILL>> | <<FILL>> |
<<FILL: functional activity, the anchor>> | <<FILL: cell-based kill or cytokine assay>> | <<FILL: cells perform intended function>> | <<FILL: release where feasible, or matrix anchor>> | <<FILL>> |
<<FILL: e.g. vector copy number>> | <<FILL: ddPCR>> | <<FILL: integration / dose surrogate>> | <<FILL: release / safety>> | <<FILL>> |
4. Marker-to-function correlation plan
For any fast or marker-based measure used to release product ahead of the slower functional assay result, state how and when the correlation to actual function is established and maintained.
| Item | Detail |
|---|---|
| Fast measure(s) relied on at release | <<FILL>> |
| Anchor functional assay | <<FILL>> |
| Correlation dataset plan | <<FILL: number of lots, how correlation is analyzed, e.g. regression of marker vs. functional result across clinical lots>> |
| Correlation acceptance threshold | <<FILL: pre-set statistical or clinical criterion>> |
| Review cadence | <<FILL: e.g. reviewed at each clinical data lock and at each major process change>> |
A fast measure used at release without an active correlation plan to the functional anchor is a marker of convenience, not a potency assurance element, and should be labeled as such in this plan until the correlation is built.
5. Reference standard
Reference the reference standard qualification and bridging protocol supporting the anchor functional assay (<<FILL: protocol ID>>); do not restate it here. Confirm every assay in the matrix that reports against a reference standard is linked to a qualified standard under that protocol.
6. Lifecycle path
| Stage | Expected potency assurance posture |
|---|---|
Early clinical (<<FILL: phase>>) | <<FILL: matrix of qualified measures; functional assay in development or qualified, run in parallel where feasible>> |
Late clinical (<<FILL: phase>>) | <<FILL: functional assay qualified and correlation data accumulating; matrix narrows as correlation strengthens>> |
| Licensure (BLA) | <<FILL: a validated, quantitative assay measuring a relevant biological activity is in place, supported by the matrix and process controls>> |
State the plan for closing any gap between the current posture and the licensure expectation, and the milestone that triggers the next stage’s review.
7. Roles and responsibilities
| Role | Responsibility |
|---|---|
| Analytical Development | Owns the matrix design, the correlation dataset, and the lifecycle plan toward a validated functional assay |
| Reference Standard custodian | Owns qualification and bridging of every reference standard used in the matrix |
| QC | Executes routine testing for each measure under GMP |
| QA | Approves this plan and any change to the matrix; owns change control when a measure is added, removed, or reweighted |
| Regulatory Affairs | Confirms the strategy aligns with current FDA and, where applicable, other regional expectations for potency assurance; manages agency interaction |
| Statistics | Designs and analyzes the marker-to-function correlation, supports the lifecycle transition criteria |
8. Governance and change control
Any change to the matrix (adding, removing, or reweighting a measure; changing which measure releases the product) is a change-controlled event, assessed for its effect on the overall potency claim and reviewed by QA and Regulatory Affairs, not an informal method update.
9. Acceptance criteria
- Every measure in the matrix has a stated purpose (release or characterization) and a documented status (qualified or validated).
- The anchor functional assay is identified and its mechanism-of-action link stated.
- A correlation plan and threshold exist for every fast measure relied on at release ahead of the functional result.
- The lifecycle path to a validated, quantitative functional assay by licensure is documented, with the gap to close stated plainly if not yet met.
- Any change to the matrix goes through change control with QA and Regulatory Affairs review.
10. References
21 CFR 600.3(s) and 21 CFR 610.10 (US potency requirements). FDA guidance on potency tests and potency assurance for cellular and gene therapy products (confirm current title and status). ICH Q6B (specifications, biological activity) and ICH Q2(R2) / Q14 (analytical validation and development).
Confirm the current title, docket, and status of the FDA potency assurance guidance against the published source before citing it in a filing.
11. Revision history
| Version | Date | Author | Summary of change |
|---|---|---|---|
<<FILL: 1.0>> | <<FILL: date>> | <<FILL: author>> | Initial issue. |
12. Approvals
| Role | Name | Signature | Date |
|---|---|---|---|
| Author | <<FILL>> | ||
| Reviewer (Analytical Development) | <<FILL>> | ||
| Approver (Quality Head) | <<FILL>> |
Filled specimen (extract)
Product: autologous gene-modified T-cell therapy, early clinical stage.
| Measurement | Assay | Reads on | Release or characterization | Status |
|---|---|---|---|---|
| Cell viability | Flow / dye exclusion | Live active cells present | Release | Qualified |
| Identity / phenotype | Flow cytometry | Correct cell population, transduction marker | Release | Qualified |
| Transgene expression | Flow / qPCR | Construct is expressed | Release | Qualified |
| Functional activity (anchor) | Cell-based cytotoxicity assay | Target-cell killing | Matrix anchor, run in parallel to release, not yet release-gating | Qualified, validation in progress |
| Vector copy number | ddPCR | Integration / dose surrogate | Release / safety | Validated |
Correlation dataset plan: transduction marker percentage and vector copy number are plotted against the cytotoxicity assay result for every clinical lot at each data lock; a pre-set Pearson correlation of at least 0.7 across 15 or more paired lot results is the threshold before the marker can be proposed as a release surrogate in place of the slower functional assay. At the current data lock (9 paired lots), the correlation is 0.61, below threshold; the functional assay therefore continues to run for every lot, reported post-release for the matrix and characterization record, with the goal of reaching threshold or moving to a faster functional format before the late clinical stage review.
Common inspection findings this plan prevents
- A marker-based release measure used as a potency surrogate with no active correlation study to the functional assay, or a correlation study that was never analyzed against a pre-set threshold.
- No documented path from a qualified matrix of measures to a validated quantitative functional assay expected by licensure.
- A change to the potency assurance matrix (dropping or reweighting a measure) made informally, without change control or Regulatory Affairs review.
- The potency assurance strategy exists as an idea in submissions text but has no controlled document QA can audit against.
How to adapt
- Populate the matrix in section 3 from your product’s actual measures; do not carry rows that do not apply to your modality.
- Set the correlation acceptance threshold in section 4 with Statistics, based on the number of paired lot results realistically available at each stage.
- Update the lifecycle path in section 6 at every major clinical data lock and at BLA planning.
- Confirm the FDA guidance reference in section 10 against its current title, docket number, and finalization status before citing it.